Compositions and methods for a barrier removal

ABSTRACT

The present invention provides an aqueous composition useful for polishing a semiconductor wafer, the wafer comprising a tantalum barrier material in the presence of a dielectric and an interconnect metal. The composition comprises an azole compound having a concentration sufficient to accelerate removal of the tantalum barrier material. In addition, the azole compound does not inhibit removal of the interconnect metal. The composition further comprises an abrasive. Also, the composition has a greater selectivity of the tantalum barrier material relative to the dielectric.

BACKGROUND OF THE INVENTION

The invention relates to chemical mechanical planarization (CMP) ofsemiconductor wafer materials and, more particularly, to CMPcompositions and methods for removing barrier materials of semiconductorwafers in the presence of dielectrics and interconnect metals.

Typically, a semiconductor wafer has a wafer of silicon and a dielectriclayer containing multiple trenches arranged to form a pattern forcircuit interconnects within the dielectric layer. The patternarrangements usually have a damascene structure or dual damascenestructure. A barrier layer covers the patterned dielectric layer and ametal layer covers the barrier layer. The metal layer has at leastsufficient thickness to fill the patterned trenches with metal to formcircuit interconnects.

CMP processes often include multiple planarization steps. For example, afirst step removes a metal layer from underlying barrier dielectriclayers. The first step polishing removes the metal layer, while leavinga smooth planar surface on the wafer with metal-filled trenches thatprovide circuit interconnects planar to the polished surface. First steppolishing removes excess interconnect metals, such as copper at aninitial high rate. After the first step removal, the second steppolishing can remove a barrier that remains on the semiconductor wafer.This second step polishing removes the barrier from an underlyingdielectric layer of a semiconductor wafer to provide a planar polishedsurface on the dielectric layer.

Unfortunately, CMP processes often result in the excess removal ofunwanted metal from circuit interconnects, a condition known as“dishing”. This dishing can result from, both first step polishing, andsecond step polishing. Dishing in excess of acceptable levels causesdimensional losses in the circuit interconnects. These “thin” areas inthe circuit interconnects attenuate electrical signals and impaircontinued fabrication of dual damascene structures.

A barrier typically is a metal, metal alloy or intermetallic compound,such as tantalum or tantalum nitride. The barrier forms a layer thatprevents migration or diffusion between layers within a wafer. Forexample, barriers prevent the diffusion of interconnect metal such ascopper or silver into an adjacent dielectric. Barrier materials must beresistant to corrosion by most acids, and thereby, resist dissolution ina fluid polishing composition for CMP. Furthermore, these barriermaterials may exhibit a toughness that resists removal by abrasiveparticles in a CMP slurry and from fixed abrasive pads.

Erosion refers to unwanted recesses in the surface of dielectric layersthat result from removing some of the dielectric layer by the CMPprocess. Erosion that occurs adjacent to the metal in trenches causesdimensional defects in the circuit interconnects. These defectscontribute to attenuation of electrical signals transmitted by thecircuit interconnects and impair subsequent fabrication of a dualdamascene structures in a manner similar to dishing. The removal rate ofthe barrier, versus, a removal rate of the metal interconnect or thedielectric layer is known as the selectivity ratio.

As discussed above, most barrier materials are difficult to remove byCMP, because the barrier materials resist removal by abrasion and bydissolution. Typical barrier removal slurries require a high abrasiveconcentration in a fluid polishing composition to remove a barriermaterial. For example, Farkas et al., in U.S. Pat. No. 6,001,730,disclose slurries for polishing copper interconnects having barrierlayers with up to 12 weight percent of an abrasive. But slurries havingthese high abrasive concentrations tend to provide detrimental erosionto the dielectric layer and result in dishing and scratching of thecopper interconnect. In addition to this, high abrasive concentrationscan result in peeling or delaminating of low-k dielectric layers fromsemiconductor wafers.

Hence, what is needed is an improved CMP composition and method forselectively removing tantalum barrier materials. In particular, there isa need for a CMP composition and method for selectively removingtantalum barrier materials with reduced dielectric erosion and reduceddishing and scratching of the metal interconnect. Furthermore, there isa desire to remove tantalum barrier materials without peeling low-kdielectric layers from semiconductor wafers.

STATEMENT OF THE INVENTION

The present invention provides an aqueous composition useful forpolishing tantalum barrier material from a semiconductor wafer. Thecomposition comprises an azole compound having a concentrationsufficient to accelerate removal of the tantalum barrier material. Inaddition, the azole compound does not inhibit removal of theinterconnect metal. The composition further comprises an abrasive. Also,the composition has a greater selectivity for the tantalum barriermaterial relative to the dielectric.

In a first aspect, the present invention provides an aqueous compositionuseful for polishing a semiconductor wafer, the wafer comprising atantalum barrier material in the presence of a dielectric and aninterconnect metal, the composition comprising: an azole compound havinga concentration sufficient to accelerate removal of the tantalum barriermaterial, the azole compound not inhibiting removal of the interconnectmetal; an abrasive; and wherein the composition has a greaterselectivity of the tantalum barrier material relative to the dielectric.

In a second aspect, the present invention provides an aqueouscomposition useful for polishing tantalum barrier material from asemiconductor wafer, comprising by weight percent 0 to 25 oxidizer, 0 to6 inhibitor for a nonferrous metal, 0 to 15 complexing agent for thenonferrous metal, 0.05 to 25 azole compound, 0.05 to 10 abrasive,wherein the composition has a selectivity of the tantalum barriermaterial relative to a dielectric of at least 10 to 1 as measured with amicroporous polyurethane polishing pad pressure measured normal to awafer of 20.7 kPa and the azole compound is selected from the groupcomprising, 1,2,4-triazole, 3-methyl-1,2,4-triazole,3,5-dimethyl-1,2,4-triazole, 1-amino-1,2,4-triazole,3-amino-1,2,4-triazole, 5-amino-3-methyl-1,2,4-triazole,3-isopropyl-1,2,4-triazole, 1,2,3-triazole, 1-methyl-1,2,3-triazole,1-amino-1,2,3-triazole, 1-amino-5-methyl-1,2,3-triazole,4,5-dimethyl-1,2,3-triazole, 1-amino-5-n-propyl-1,2,3-triazole,1-(β-aminoethyl)-1,2,3-triazole, 1-methyltetrazole, 2-methyltetrazole,5-amino-1H-tetrazole, 5-amino-1-methyltetrazole,1-(β-aminoethyl)tetrazole, a substituted triazole or tetrazole compoundhaving an electron-donating substituent, and a mixture thereof.

In a third aspect, the present invention provides a chemical mechanicalplanarization method for polishing a semiconductor wafer, the wafercomprising a tantalum barrier material in the presence of a dielectricand an interconnect metal, the method comprising: contacting the waferwith a polishing composition, the polishing composition containing anazole compound and an abrasive, the azole compound having aconcentration sufficient to accelerate removal of the tantalum barriermaterial, the azole compound not inhibiting removal of the interconnectmetal; and polishing the wafer with a polishing pad to remove thetantalum barrier material at a removal rate greater than a removal ratefor the dielectric as expressed in angstroms per minute.

DETAILED DESCRIPTION

The solution and method provide unexpected selectivity for removingtantalum barrier materials. The solution relies upon an azole compoundan abrasive to selectively remove tantalum barrier materials. Thesolution selectively removes barrier materials with reduced dielectricerosion and reduced dishing and scratching of the metal interconnects,such as copper. Furthermore, the solution removes tantalum barriermaterials without peeling or delaminating low-k dielectric layers fromsemiconductor wafers.

For purposes of this specification, tantalum barrier refers to tantalum,tantalum-containing alloy, tantalum-base alloys and tantalumintermetallics. The solution has particular effectiveness for tantalum,tantalum-base alloys and tantalum intemetallics, such as tantalumcarbides, nitrides and oxides. The slurry is most effective foraccelerating the removal of tantalum barriers from patternedsemiconductor wafers without inhibiting the removal rate of metalinterconnects.

The azole compound is defined herein as a compound containing two ormore nitrogen atoms in a conjugated cyclic compound. The conjugatedcyclic compound further comprises at least one double bond between theat least two nitrogen atoms. The nitrogen atoms in the conjugated cycliccompound may be adjacent to each other or may be separated by otheratoms. Also, the azole compound may be substituted by other groups alongthe cyclic ring members. The preferred substituting groups are electrondonating groups. For purposes of the specification, the term“electron-donating” refers to a chemical group bonded to a substancethat transfers electron density to that substance. F. A. Carey and R. J.Sundberg, in Advanced Organic Chemistry, Part A: Structure andMechanisms, 3^(rd) Edition New York: Plenum Press (1990), p. 208 and546-561 provide a more detailed description of electron-donatingsubstituents. Electron-donating substituents include, for example,amino, hydroxyl (—OH), alkyl, substituted alkyl, hydrocabon radical,substituted hydrocarbon radical, amido, and aryl. Theseelectron-donating substituents accelerate removal of tantalum-containingbarrier materials. In theory, when the azole compound is adsorbed ontothe barrier surface, such as TaN or Ta, the electrons flow between theat least two nitrogen atoms through the conjugate bonds. Consequently,the azole compounds have a strong affinity to the barrier surface. Thisaffinity for the barrier surface is theorized to accelerate the barrierremoval rate with limited use of abrasives.

Preferred azole compounds include, triazole compounds, for example,1,2,4-triazole, 3-methyl-1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole,1-amino-1,2,4-triazole, 3-amino-1,2,4-triazole,5-amino-3-methyl-1,2,4-triazole, 3 -isopropyl-1,2,4-triazole,1,2,3-triazole, 1-methyl-1,2,3-triazole, 1-amino-1,2,3-triazole,1-amino-5-methyl-1,2,3-triazole, 4,5-dimethyl-1,2,3-triazole,1-amino-5-n-propyl-1,2,3-triazole, 1-(β-aminoethyl)-1,2,3-triazole, asubstituted triazole compound having an electron-donating substituent,and mixtures thereof. Further, other azole compounds include, tetrazolecompounds, for example, 1-methyltetrazole, 2-methyltetrazole,5-amino-1H-tetrazole, 5-amino-1-methyltetrazole,1-(β-aminoethyl)tetrazole, a substituted tetrazole compound having anelectron-donating substituent, and mixtures thereof. Particularlyeffective azole compounds for accelerating the removal of tantalumbarriers are 1,2,4-triazole and 3-amino-1,2,4-triazole.

Advantageously, the azole compound may be present in the solution in arange of concentrations, for example from 0.05 to 25 weight percent.This specification expresses all concentrations in weight percent. Asingle type of azole compound may be present, or a mixture of azolecompounds may be used. Most advantageously, the solution contains 0.1 to10 weight percent azole compounds and for most applications, azolecompound concentrations of 1 to 5 weight percent provide sufficientbarrier removal rates. Most preferably, the concentration of the azolecompound is 2 weight percent.

The polishing composition contains 0.05 to 10 weight percent abrasive tofacilitate barrier layer. Within this range, it is desirable to have theabrasive present in an amount of greater than or equal to 0.1 weightpercent, and preferably greater than or equal to 0.5 weight percent.Also, desirable within this range is an amount of less than or equal to5 weight percent, and preferably less than or equal to 3 weight percent.Most preferably, the abrasive concentration is from 1 to 2 weightpercent.

The abrasive has an average particle size of less than or equal to 50nanometers (nm) for preventing excessive metal dishing and dielectricerosion. For purposes of this specification, particle size refers to theaverage particle size of the abrasive. More preferably, it is desirableto use a colloidal abrasive having an average particle size of less thanor equal to 40 nm. Further, minimal dielectric erosion and metal dishingadvantageously occurs with colloidal silica having an average particlesize of less than or equal to 30 nm. Decreasing the size of thecolloidal abrasive to less than or equal to 30 nm, tends to improve theselectivity of the polishing composition, but, it also tends to decreasethe barrier removal rate. In addition, the preferred colloidal abrasivemay include additives, such as dispersants, surfactants and buffers toimprove the stability of the colloidal abrasive. One such colloidalabrasive is colloidal silica from Clariant S. A., of Puteaux, France.

The polishing composition includes the abrasive for “mechanical” removalof barrier layers. Example abrasives include inorganic oxides, metalborides, metal carbides, metal nitrides, polymer particles and mixturescomprising at least one of the foregoing. Suitable inorganic oxidesinclude, for example, silica (SiO₂), alumina (Al₂O₃), zirconia (ZrO₂),ceria (CeO₂), manganese oxide (MnO₂), or combinations comprising atleast one of the foregoing oxides. Modified forms of these inorganicoxides, such as, polymer-coated inorganic oxide particles and inorganiccoated particles may also be utilized if desired. Suitable metalcarbides, boride and nitrides include, for example, silicon carbide,silicon nitride, silicon carbonitride (SiCN), boron carbide, tungstencarbide, zirconium carbide, aluminum boride, tantalum carbide, titaniumcarbide, or combinations comprising at least one of the foregoing metalcarbides, boride and nitrides. Diamond may also be utilized as anabrasive if desired. Alternative abrasives also include polymericparticles and coated polymeric particles. The preferred abrasive issilica.

Advantageously, the use of the azole compound facilitates polishing withlow abrasive concentrations. The polishing solutions containing azolecompounds and low abrasive concentrations can readily remove thetantalum barrier material at a rate of at least 10 times greater thanthe dielectric removal rate as expressed in angstroms per minute. Morepreferably, the solution of the present invention can readily remove thetantalum barrier material at a rate of at least 100 times greater thanthe dielectric removal rate. Most preferably, the solution of thepresent invention can readily remove the tantalum barrier material at arate of at least 1000 times greater than the dielectric removal rate.Further, the polishing solutions containing azole compounds and lowabrasive concentrations can readily remove the tantalum barrier materialat a rate of at least 2 times greater than the metal removal rate asexpressed in angstroms per minute. More preferably, the polishingsolutions of the present invention can readily remove the tantalumbarrier material at a rate of at least 5 times greater than the metalremoval rate as expressed in angstroms per minute. Most preferably, thepolishing solutions of the present invention can readily remove thetantalum barrier material at a rate of at least 10 times greater thanthe metal removal rate as expressed in angstroms per minute. Note, theazole compounds of the present invention accelerate the removal of thetantalum barrier material. The azole compounds of the present inventionare not inhibitors for the interconnect metal. In other words, the azolecompounds of the present invention accelerate the removal rate of thetantalum barrier material without inhibiting removal of the interconnectmetal.

The azole compounds provide efficacy over a broad pH range in solutionscontaining a balance of water. This solution's useful pH range extendsfrom at least 2 to 13. In addition, the solution advantageously reliesupon a balance of deionized water to limit incidental impurities. The pHof the polishing fluid of this invention is preferably from 7 to 12,more preferably from pH 8-10. If the solution's pH is less than 7, anoxidizer may be added to enhance the azole efficacy for removing thebarrier material. The bases used to adjust the pH of the slurry of thisinvention may be a base containing ammonium ion, such as ammoniumhydroxide, bases containing alkyl-substituted ammonium ions, basescontaining alkali metal ion, bases containing alkali-earth metal ion,bases containing group IIIB metal ion, bases containing group IVB metalion, bases containing group VB metal ion and salts containing transitionmetal ion. The designed pH in the basic range is not only for removal ofthe barrier surface, but also helpful for the slurry of this inventionto be stable. For the polishing slurry, the pH may be adjusted by aknown technique. For example, an alkali may be directly added to aslurry in which a silica abrasive is dispersed and an organic acid isdissolved. Alternatively, a part or all of an alkali to be added may beadded as an organic alkali salt. Examples of an alkali, which may beused, include alkali metal hydroxides such as potassium hydroxide,alkali metal carbonates such as potassium carbonate, ammonia and amines.

Optionally, the solution contains 0 to 25 weight percent oxidizer.Advantageously, the optional oxidizer is in the range of 0 to 15 weightpercent. The oxidizer is particularly effective at assisting thesolution in removing tantalum oxide films that can form at low pHranges. The oxidizing agent can be at least one of a number of oxidizingcompounds, such as hydrogen peroxide (H₂O₂), monopersulfates, iodates,magnesium perphthalate, peracetic acid and other per-acids, persulfates,bromates, periodates, nitrates, iron salts, cerium salts, Mn (III), Mn(IV) and Mn (VI) salts, silver salts, copper salts, chromium salts,cobalt salts, halogens hypochlorites and a mixture thereof. Furthermore,it is often advantageous to use a mixture of oxidizer compounds. Whenthe polishing slurry contains an unstable oxidizing agent such as,hydrogen peroxide, it is often most advantageous to mix the oxidizerinto the slurry at the point of use.

Optionally, the solution contains 0 to 6 weight percent inhibitor tocontrol interconnect removal rate by static etch or other removalmechanism. Adjusting the concentration of an inhibitor adjusts theinterconnect metal removal rate by protecting the metal from staticetch. Advantageously, the solution contains an optional 0.02 to 5 weightpercent inhibitor for inhibiting static etch of copper or silverinterconnects. The inhibitor may consist of a mixture of inhibitors.Azole inhibitors are particularly effective for copper and silverinterconnects. Typical azole inhibitors include benzotriazole (BTA),mercaptobenzothiazole (MBT), tolytriazole and imidazole. BTA is aparticularly effective inhibitor for copper and silver. Note, theseinhibitors are specifically excluded from the definition of “azole”compounds for the purposes of this application. In other words, theazole compounds of the present invention are chosen for their selectiveability to remove barrier materials and not for the purposes ofinhibiting the removal rate of metal interconnects.

In addition to the inhibitor, the solution may contain 0 to 20 weightpercent complexing agent for the nonferrous metal. The complexing agent,when present, prevents precipitation of the metal ions formed bydissolving the nonferrous metal interconnects. Most advantageously, thesolution contains 0 to 10 weight percent complexing agent for thenonferrous metal. Example complexing agents include acetic acid, citricacid, ethyl acetoacetate, glycolic acid, lactic acid, malic acid, oxalicacid, salicylic acid, sodium diethyl dithiocarbamate, succinic acid,tartaric acid, thioglycolic acid, glycine, alanine, aspartic acid,ethylene diamine, trimethyl diamine, malonic acid, gluteric acid,3-hydroxybutyric acid, propionic acid, phthalic acid, isophthalic acid,3-hydroxy salicylic acid, 3,5-dihydroxy salicylic acid, gallic acid,gluconic acid, pyrocatechol, pyrogallol, tannic acid, including, saltsand mixtures thereof. Advantageously, the complexing agent is selectedfrom the group consisting of acetic acid, citric acid, ethylacetoacetate, glycolic acid, lactic acid, malic acid, oxalic acid andmixtures thereof. Most advantageously, the complexing agent is citricacid.

The polishing fluid of the present invention is applicable to anysemiconductor substrate containing a conductive metal, such as copper,aluminum, tungsten, platinum, palladium, gold, or iridium; a barrier orliner film, such as tantalum, tantalum nitride, titanium, or titaniumnitride; and an underlying dielectric layer. For purposes of thespecification, the term dielectric refers to a semi-conducting materialof dielectric constant, k, which includes low-k and ultra-low kdielectric materials. The present methods removes tantalum barriermaterials with little effect on conventional dielectrics and low-kdielectric materials. Since the solutions provide effective barrierremoval rates with low concentrations of abrasives at low pressures(i.e., less than 20.7 kPa) and high tantalum selectivity, it facilitatespolishing with low dielectric erosion rates. The solution and method areexcellent for preventing erosion of multiple wafer constituents, forexample, porous and nonporous low-k dielectrics, organic and inorganiclow-k dielectrics, organic silicate glasses (OSG), fluorosilicate glass(FSG), carbon doped oxide (CDO), tetraethylorthosilicate (TEOS) and asilica derived from TEOS.

The polishing solution may also include levelers such as, ammoniumchloride, to control surface finish of the interconnect metal. Inaddition to this, the solution optionally may contain a biocide forlimiting biological contamination. For example, Kordek® MLX microbicide2-Methyl-4-isothiazolin-3-one in water (Rohm and Haas Company) providesan effective biocide for many applications. The biocide is typicallyused in the concentration prescribed by the supplier.

The solution provides a tantalum nitride to dielectric and metalselectivity of at least 10 to 1 and at least 2 to 1, respectively, asmeasured with a microporous polyurethane polishing pad pressure measurednormal to a wafer of 20.7 kPa. A particular polishing pad useful fordetermining selectivity is the Politex microporous polyurethanepolishing pad. Adjusting the abrasive and azole compound concentrationsadjusts the tantalum barrier removal rate. Adjusting the inhibitor,oxidizer, complexing agent and leveler concentrations adjusts the etchrate of the interconnect metals.

EXAMPLES

In the Examples, numerals represent examples of the invention andletters represent comparative examples. In addition, all examplesolutions contained 0.01 weight percent Kordek® MLX microbicide2-Methyl-4-isothiazolin-3-one in water and 0.01 ammonium chloridebrightener.

Example 1

This experiment measured removal rates of the TaN barrier, a dielectriclayer of TEOS and copper from a semiconductor wafer. In particular, thetest determined the effect of specific azole compounds and abrasives ina second step polishing operation. A Strausbaugh polishing machine usinga Politex polyurethane polishing pad (Rodel, Inc.) under downforceconditions of about 3 psi (20.7 kPa) and a polishing solution flow rateof 200 cc/min, a platen speed of 120 RPM and a carrier speed of 114 RPMplanarized the samples. The polishing solutions had a pH of 9 adjustedwith KOH and HNO_(3.) All solutions contained deionized water. Inaddition, polishing solutions included 1 weight percent silica abrasiveshaving an average particle size of 50 nm. TABLE 1 Second Polishing StepResults Citric Abrasive BTA Acid TaN TEOS Cu Test Additive Wt. % (wt. %)(wt. %) (wt. %) Å/min Å/min Å/min A None — 0 0.1 0 6 −3 38 B None — 1 00.15 26 32 116 C None — 1 0.2 0.15 163 39 91 D 1,2,4-triazole 2 0 0.1 0−8 −1.4 33 E 3-amino- 2 0 0.1 0 −21 −5.1 49 1,2,4-triazole 11,2,4-triazole 2 1 0.1 0 1995 −0.2 135 2 3-amino- 2 2 0.1 0 2223 −0.4174 1,2,4-triazole

As illustrated in Table 1, high removal rates of the TaN barrier filmare obtained with a polishing fluid that includes an azole compound andan abrasive. In particular, second polishing step fluids containing anabrasive and 1,2,4-triazole or 3-amino-1,2,4-triazole (Tests 1 and 2,respectively) provided excellent removal rates for the TaN, namely, atleast 1995 angstroms per minute (Å/min). Polishing fluids containing anabrasive without an azole compound (Comparative Solutions, B and C) andpolishing fluids containing an azole compound without an abrasive(Comparative Solutions, D and E) showed lower rates of TaN removal andpoor removal selectivity relative to the dielectric (TEOS) and to themetal (Cu). Note, the negative removal rates of the TaN and thedielectric are within the defined tolerances of the polishing machineand indicate no detectable TaN and/or TEOS loss. When an azole compoundwas present in the polishing fluid with an abrasive, the removalselectivity of the TaN relative to the dielectric was 1995 to 1 and 2223to 1, for Tests 1 and 2, respectively. The removal selectivity of theTaN to the metal was 15 to 1 and 13 to 1, for Tests 1 and 2,respectively. Note, the selectivity discussed is at the test conditionsfor the Example as defined above. The selectivity may vary with changesmade to the test parameters.

The results shown in Table 1 indicates that excellent removal of thebarrier film (TaN) along with commensurate removal selectivity relativethe metal film (Cu) and the dielectric layer (TEOS) is obtained whenusing polishing fluids containing azole compounds and an abrasive. Anazole compound present at about 2 weight percent was useful for thisremoval, providing an excellent barrier removal rate and removalselectivity. All of the polishing fluids contained an abrasives contentof 1 to 2 weight percent, an amount that is well below the abrasivesconcentration typically used in conventional second polishing stepfluids.

The solution and method provide excellent selectivity for removingtantalum barrier materials such as tantalum, tantalum nitride andtantalum oxide. The solution selectively removes tantalum barriermaterials with reduced dielectric erosion. For example, the solution canremove tantalum barriers without a detectable TEOS loss and withoutpeeling or delaminating low-k dielectric layers. In addition, thesolution reduces dishing and scratching of copper interconnects. Also,the azole compounds of the present invention accelerate the removal ofthe tantalum barrier material without inhibiting removal of theinterconnect metal.

1. An aqueous composition useful for polishing a semiconductor wafer,the wafer comprising a tantalum barrier material in the presence of adielectric and an interconnect metal, the composition comprising: anazole compound having a concentration sufficient to accelerate removalof the tantalum barrier material, the azole compound not inhibitingremoval of the interconnect metal; an abrasive; and wherein thecomposition has a greater selectivity of the tantalum barrier materialrelative to the dielectric.
 2. The composition of claim 1 wherein theconcentration is 0.05 to 25 weight percent of the azole compound.
 3. Thecomposition of claim 1 wherein the composition comprises 0.05 to 10weight percent of the abrasive.
 4. The composition of claim 1 whereinthe composition has a selectivity of the tantalum barrier materialrelative to a metal of at least 2 to 1 as measured with a microporouspolyurethane polishing pad pressure measured normal to a wafer of 20.7kPa.
 5. The composition of claim 1 wherein the azole compound isselected from the group comprising: triazole, tetrazole, and a mixturethereof.
 6. The composition of claim 5 wherein the triazole is selectedfrom the group comprising: 1,2,4-triazole, 3-methyl-1,2,4-triazole,3,5-dimethyl-1,2,4-triazole, 1-amino-1,2,4-triazole,3-amino-1,2,4-triazole, 5-amino-3-methyl-1,2,4-triazole,3-isopropyl-1,2,4-triazole, 1,2,3-triazole, 1-methyl-1,2,3-triazole,1-amino-1,2,3-triazole, 1-amino-5-methyl-1,2,3-triazole,4,5-dimethyl-1,2,3-triazole, 1-amino-5-n-propyl-1,2,3-triazole,1-(β-aminoethyl)-1,2,3-triazole, a substituted triazole compound havingan electron-donating substituent, and a mixture thereof.
 7. Thecomposition of claim 5 wherein the tetrazole is selected from the groupcomprising: 1-methyltetrazole, 2-methyltetrazole, 5-amino-1H-tetrazole,5-amino-1-methyltetrazole, 1-(β-aminoethyl)tetrazole, a substitutedtetrazole compound having an electron-donating substituent, and amixture thereof.
 8. An aqueous composition useful for polishing tantalumbarrier material from a semiconductor wafer, comprising by weightpercent 0 to 25 oxidizer, 0 to 6 inhibitor for a nonferrous metal, 0 to15 complexing agent for the nonferrous metal, 0.05 to 25 azole compound,0.05 to 12 abrasive, wherein the composition has a selectivity of thetantalum barrier material relative to a dielectric of at least 10 to 1as measured with a microporous polyurethane polishing pad pressuremeasured normal to a wafer of 20.7 kPa and the azole compound isselected from the group comprising, 1,2,4-triazole,3-methyl-1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole,1-amino-1,2,4-triazole, 3-amino-1,2,4-triazole,5-amino-3-methyl-1,2,4-triazole, 3-isopropyl-1,2,4-triazole,1,2,3-triazole, 1-methyl-1,2,3-triazole, 1-amino-1,2,3-triazole,1-amino-5-methyl-1,2,3-triazole, 4,5-dimethyl-1,2,3-triazole,1-amino-5-n-propyl-1,2,3-triazole, 1-(β-aminoethyl)-1,2,3-triazole,1-methyltetrazole, 2-methyltetrazole, 5-amino-1H-tetrazole,5-amino-1-methyltetrazole, 1-(β-aminoethyl)tetrazole, a substitutedtriazole or tetrazole compound having an electron-donating substituent,and a mixture thereof.
 9. A chemical mechanical planarization method forpolishing a semiconductor wafer, the wafer comprising a tantalum barriermaterial in the presence of a dielectric and an interconnect metal, themethod comprising: contacting the wafer with a polishing composition,the polishing composition containing an azole compound and an abrasive,the azole compound having a concentration sufficient to accelerateremoval of the tantalum barrier material, the azole compound notinhibiting removal of the interconnect metal; and polishing the waferwith a polishing pad to remove the tantalum barrier material at aremoval rate greater than a removal rate for the dielectric as expressedin angstroms per minute.
 10. The method of claim 9 wherein the azolecompound is selected from the group comprising: 1,2,4-triazole,3-methyl-1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole,1-amino-1,2,4-triazole, 3-amino-1,2,4-triazole,5-amino-3-methyl-1,2,4-triazole, 3-isopropyl-1,2,4-triazole,1,2,3-triazole, 1-methyl-1,2,3-triazole, 1-amino-1,2,3-triazole,1-amino-5-methyl-1,2,3-triazole, 4,5-dimethyl-1,2,3-triazole,1-amino-5-n-propyl-1,2,3-triazole, 1-(β-aminoethyl)-1,2,3 -triazole,1-methyltetrazole, 2-methyltetrazole, 5-amino-1H-tetrazole,5-amino-1-methyltetrazole, 1-(β-aminoethyl)tetrazole, a substitutedtriazole or tetrazole compound having an electron-donating substituent,and a mixture thereof.